NAME

       aio_write - asynchronous write to a file (REALTIME)

SYNOPSIS

       #include <aio.h>

       int aio_write(struct aiocb *aiocbp);

DESCRIPTION

       The  aio_write()  function  shall  write  aiocbp->aio_nbytes  to  the file associated with
       aiocbp->aio_fildes from the buffer pointed to  by  aiocbp->aio_buf.   The  function  shall
       return  when  the write request has been initiated or, at a minimum, queued to the file or
       device.

       If prioritized I/O is supported for this file, then the asynchronous  operation  shall  be
       submitted   at  a  priority  equal  to  the  scheduling  priority  of  the  process  minus
       aiocbp->aio_reqprio.

       The aiocbp argument may be used as an argument to aio_error() and aio_return() in order to
       determine  the error status and return status, respectively, of the asynchronous operation
       while it is proceeding.

       The  aiocbp  argument  points  to  an  aiocb  structure.  If  the  buffer  pointed  to  by
       aiocbp->aio_buf or the control block pointed to by aiocbp becomes an illegal address prior
       to asynchronous I/O completion, then the behavior is undefined.

       If O_APPEND is not set for the file descriptor aio_fildes, then  the  requested  operation
       shall  take  place  at  the  absolute  position  in the file as given by aio_offset, as if
       lseek() were called immediately prior to the operation with an offset equal to  aio_offset
       and  a  whence  equal  to  SEEK_SET.  If  O_APPEND  is  set for the file descriptor, write
       operations append to the file in the same order as the calls were made. After a successful
       call  to  enqueue an asynchronous I/O operation, the value of the file offset for the file
       is unspecified.

       The aiocbp->aio_lio_opcode field shall be ignored by aio_write().

       Simultaneous asynchronous operations using the same aiocbp produce undefined results.

       If synchronized I/O is  enabled  on  the  file  associated  with  aiocbp->aio_fildes,  the
       behavior  of  this function shall be according to the definitions of synchronized I/O data
       integrity completion, and synchronized I/O file integrity completion.

       For any system action that changes the process memory space while an asynchronous  I/O  is
       outstanding to the address range being changed, the result of that action is undefined.

       For regular files, no data transfer shall occur past the offset maximum established in the
       open file description associated with aiocbp->aio_fildes.

RETURN VALUE

       The aio_write() function shall return the value zero to the calling  process  if  the  I/O
       operation  is  successfully  queued; otherwise, the function shall return the value -1 and
       set errno to indicate the error.

ERRORS

       The aio_write() function shall fail if:

       EAGAIN The requested asynchronous I/O operation was not  queued  due  to  system  resource
              limitations.

       Each  of the following conditions may be detected synchronously at the time of the call to
       aio_write(),  or  asynchronously.   If  any  of  the   conditions   below   are   detected
       synchronously, the aio_write() function shall return -1 and set errno to the corresponding
       value. If any of the conditions below are detected asynchronously, the  return  status  of
       the  asynchronous  operation  shall be set to -1, and the error status of the asynchronous
       operation is set to the corresponding value.

       EBADF  The aiocbp->aio_fildes argument is not a valid file descriptor open for writing.

       EINVAL The  file  offset  value  implied   by   aiocbp->aio_offset   would   be   invalid,
              aiocbp->aio_reqprio  is  not  a  valid  value,  or aiocbp->aio_nbytes is an invalid
              value.

       In the case that the aio_write() successfully queues the I/O operation, the return  status
       of  the asynchronous operation shall be one of the values normally returned by the write()
       function call. If the operation is successfully queued but  is  subsequently  canceled  or
       encounters  an  error, the error status for the asynchronous operation contains one of the
       values normally set by the write() function call, or one of the following:

       EBADF  The aiocbp->aio_fildes argument is not a valid file descriptor open for writing.

       EINVAL The file offset value implied by aiocbp->aio_offset would be invalid.

       ECANCELED
              The requested I/O was  canceled  before  the  I/O  completed  due  to  an  explicit
              aio_cancel() request.

       The following condition may be detected synchronously or asynchronously:

       EFBIG  The  file is a regular file, aiobcp->aio_nbytes is greater than 0, and the starting
              offset in aiobcp->aio_offset is at or beyond the offset maximum in  the  open  file
              description associated with aiocbp->aio_fildes.

       The following sections are informative.

EXAMPLES

       None.

APPLICATION USAGE

       The  aio_write() function is part of the Asynchronous Input and Output option and need not
       be available on all implementations.

RATIONALE

       None.

FUTURE DIRECTIONS

       None.

SEE ALSO

       aio_cancel() , aio_error() , aio_read() , aio_return() ,  close()  ,  exec()  ,  exit()  ,
       fork()   ,   lio_listio()   ,   lseek()  ,  write()  ,  the  Base  Definitions  volume  of
       IEEE Std 1003.1-2001, <aio.h>

COPYRIGHT

       Portions of this text are reprinted and  reproduced  in  electronic  form  from  IEEE  Std
       1003.1,  2003  Edition,  Standard  for Information Technology -- Portable Operating System
       Interface (POSIX), The Open Group Base Specifications Issue 6, Copyright (C) 2001-2003  by
       the  Institute  of  Electrical  and  Electronics Engineers, Inc and The Open Group. In the
       event of any discrepancy between this version and the original IEEE  and  The  Open  Group
       Standard,  the  original  IEEE  and  The  Open Group Standard is the referee document. The
       original Standard can be obtained online at http://www.opengroup.org/unix/online.html .